Process of producing cresol



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Patented Feb. EU, TARA.

IRA H. DERBY AND WILLIAM HIGIBURG, 01E INDIANAPOLIS, INDIANA, ASSIGNORS TO PETER. C. REILLY, 01E INDIANAPOLIS, INDIANA.

PROCESS OF PRODUCING CRESOJL.

No Drawing.

To all W/IOIIZ it may concern:

Beit known that we, IRA H. DERBY and VILLIAM HIGBURG, citizens of the United States, residing at Indianapolis, in the county of Marion and State of Indiana, have invented certain new and useful Processes of Producing Cresol, of which the following is a specification.

The present in ention relates to the pro duction of pure cresol fromcrude tar acids or from the oil containing crude tar acids distilled from coal tar, and has for its object to produce a good yield of strictly pure cresol free from phenol, free from pyridin. free from xylenols, free from water, free from the substances which, upon standing, lead to the development of pinkish or brownish color.

The method of producing cresol heretofore generally used, involves the extraction of tar acids from the crude oils by means of a caustic soda solution. the separation of the aqueous solution from the oily liquor. the subsequent boiling of the solution for a considerable time to remove pyridin and other bases and the various hydrocarbons that remain to a small extent dissolved in or mixed with the alkaline solution of the tar acids, or the blowing of steam through the liquid to drive off the pyridin, hydrocarbons, etc. The purified alkaline solution is then treated with an acid such as sulfuric. carbonic or an acid salt such as a bisulfate or bicarbonate to set free the partially purified'tar acids, which are separated from the acidilied aqueous solution and then fractionally distilled and the fraction distilling over between 175 to 215 C., is separately collected. The resulting product constitutes a more or less impure cresol, which contains some other phenols, including xylenol and a number of other impurities. In the above process it has heretofore been proposed to employ, instead of the crude tar acids, a solution made by treating crude cresylic acid with caustic soda. The products produced in these processes were not entirely pure.

.In accordance with the present process, we treat the crude tar acids with an alkali, such as caustic soda, or we treatcrude cresylic acid with caustic soda. The. crude tar acids employed may be the tar acid from the napthalene fraction of coal tar distilling below about 25U-or 270" (1. Of course, in-

Application filed November 29, 1920. Serial No. 427,128.

stead of caustic soda, other alkalies can be used. such as caustic potash or milk of lime. The solution thus obtained is boiled or has steam blown through it at the boiling point or under pressure until the distillate comes over clear and free from odor of pyridin bases or hydrocarbon. The boiled liquid is then acidulated with a small excess of dilute sulfuric acid or carbonic acid or a bicarbonate or other acid material, and the oily layer is separated from the aqueous layer. The partially refined crude tar acids are then fractionally distilled, the fraction commg over between-1T5 and 215 C., being separately collected, this fraction containing the bulk of the cresol.

The above part of the process is old and well known.

The cresol fraction is, according to the present invention, treated with a caustic,

alkali in small quantity. About 5 to 10% of the chemically equivalent quantity of caustic soda (more or less) can be conveniently employed. The solution of the causticv soda in the tar acids may be hastened by grinding them together in a ball mill, or by heating the mixture, or both. The re sulting mixture should be homogeneous. The object of the caustic soda is to unite with small quantities of phenol, xylenol, sulfur compounds and other impurities. The result ing mixture is cooled and is mixed with a solvent, such as benzol or toluol. Xylol may be used. but less advantageously. The solvent liquid should boil below 140 C. Equal parts of the mixture and the solvent may be used. This produces a homogeneous liquid, and to this liquid is added such an amount of Water as will dissolve the alkali metal compounds. An amount of water equal to one-half of the bulk of the solution may conveniently be used. After mixing thoroughly, and settling the aqueous layer is separated from the non-aqueous layer and the aqueous layer can be worked up for producing carbolic acid in the well known manner. The oily layer containing the benzol or other solvent is then fractionally distilled first to recover the benzol or other solvent for further use. After the benzol has distilled off, a first tar acid fraction distilling between about 100 and about 195 C., is collected, and a second fraction distilling from 195 to 200 0.. is collected. This second fraction may be redistilled, if necessary, and the fraction boiling between about 192 and 205 C., 1s collected, constituting the finished product, pure cresol.

We have found that in distilling the henzol from the solution, the entire amount of water in the solution is removed and this improvement is one of more or less general application.

The product remaining from the distillation, after collecting the fractionboiling atbetween 195 and 200 C., contains sodium xylenol, also some sulfur compounds and other acid bodies, together with impurities having a disagreeable odor and usually some cresolate, and can be worked up in any suitable manner.

We call attention to the fact that the invention is not limited to the specific example herein given, which is given for the purpose of illustration andexplanation.

W e claim:

1. In the process of producing pure cresol from crude cresylic acid by adding an excess of alkali, and distilling away substantially all of the pyridin and odorous hydrocarbons contained therein, acidifying the resulting liquor, separating the aqueous fraction from the oily fraction, redistilling and collecting the fraction boiling between approximately 175 and 215 C., the improvement which comprises then adding a small part only of the amount of caustic alkali necessary for combining with all of the phenolic bodies present, and adding a non-water soluble liquid solvent for cresol, the boiling point of said solvent being considerabl different from that of cresol, then mixing the resulting mass with water, separating the aqueous portion from the solution of cresol and subsequently sep arating the cresol from the solvent.

2. A process of roducing pure cresol from crude tar aci s which comprises the steps of adding a small fraction of the chemically equivalent quantity of a caustic alkali and causing the same to react, cooling and adding water insoluble, liquid, aromatic hydrocarbon solvent, then mixing with water and separating the aqueous material from the non-aqueousfraction'.

3. In the process of producing pure cresol from crude cresylic acid by adding an excess of alkali, and distilling away substantially all of the pyridin and odorous hydrocarbons contained therein, acidifying the resulting liquor, separating the aqueous fraction from the oily fraction, redistilling and collecting the fraction boiling between approximately 175 and 215 C., the improvement which comprises then adding a small part only of the amount of caustic alkali, necessary for combining with all of the henolic bodies present, and adding a water insoluble liquid hydrocarbon of the aromatic series which is a solvent for cresol, then mixing the resulting mass with water, separating the aqueous portion from the solution of cresol.

4. In the purification of tar acids, the step of distilling the solvent from the solution of purified tar acids in an aromatic hydrocarbon solvent having a boiling point not over about 140 C., whereby the water present is also driven oil.

5. In the purification of tar acids, the

\ step of distilling the solvent from the solution of purified tar acids in benzene, whereby the water present is also driven off.

6. In the preparation of cresol from redistilled and partially purified tar acids, the step of grinding the said material with a small fraction only of the quantity of caustic alkali necessary to combine with all the tar acids. 1

7. In-the preparation of cresol from redistilled and partially purified tar acids, the step offl grinding the said material with caustic alkali in amount corresponding to not greatly over 10% of the amount necessary to combine with all of the phenolic bodies therein, while heating.

8. In the preparation of cresol from redistilled and partially purified tar acids,

the steps of grinding the said material with caustic alkali, and subsequently mixing with an aromatic hydrocarbon of the benzene series as a solvent, and then adding water.

9. In the process of producin pure cresol from crude cresylic acid by a ding an excess of alkali, and distillin away substantially all of the pyridin an odorous hydrocarbons contained therein, acidifying the resulting liquor, separatin the aqueous fraction from the oily fractlon, redistilling and collecting the fraction boiling between .approximately 175 and 215 0., the improvement which comprises then adding an amount of caustic alkali not greatly in excex of 10% of the amount of caustic alkali necessary for combining with all of the phenolic bodies present, and adding a nonwater-soluble, liquid solvent for cresol, the boiling oint of said solvent being considerably dllibrent from that of cresol, then mixing the resulting mass with water, separating the aqueous portion from the solution of cresol and subsequently separating the cresol from the solvent.

10. A process of producing pure cresol from crude cresylic acid-which comprises adding to the partially purified tar acids boiling approximately between 175 and 215 an amount of caustic alkali 'corresponding to not greatly in excess of 10% of the amount of caustic alkali necessary for combining with all of the phenolic bodies present and adding a hydrocarbon of the benzene series as a solvent for the cresol, then mixing the resulting mass with Water, sepnaaaeea 'arating the aqueous portion from the solution of cresol and subsequently separating the cresol from the solvent.

11. A process of producing pure cresol from crude tar acids Which comprises the steps of adding an .amount of caustic alkali not greatly in excess of 10% of the chemically equivalent quantity of a caustic alkali and causing the same to react, cooling and adding water insoluble, liquid, aromatic hydrocarbon solvent, then mixing with Water and separating the aqueous material from the non-aqueous fraction. A

12. A process of producing pure cresol from crude tar acids which comprises the steps of adding not substantially more than 10% of the chemically equivalent of caustic alkali and causing the same to react, cooling and adding a hydrocarbon of th benzene series as solvent, then mixing With Water separating the aqueous from the quantity non-aqueous layer and distilling the solvent from the non-aqueous portion and then distilling the pure cresol therefrom.

13. A process of producing pure cresol from crude cresylic acid Wlnch comprises adding-to the partially purified tar acids boiling approximately between 17 5 and 215 (3., not substantially more than 10% of the amount of caustic alkali necessary for combining with all the phenolic bodies present and adding hydrocarbon of the benzene series Which is a solvent for cresol, then mixing the resulting mass with Water separating the aqueous portion from the solution of cresol and subsequently separating the creso]. from the solvents.

In testimony whereof We have signed our names to this specification.

IRA H, DERBY. WILLIAM HIGBURG.

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